In the protease inhibitor era, AIDS-associated opportunistic infections have become less common and more treatable, but they remain an important cause of death in patients infected with HIV. Thus, we continue our work on their diagnosis, prevention and treatment. In cytomegalovirus (CMV) retinitis, the effects of the new highly active anti-HIV regimens on the course of CMV retinitis are being evaluated in a collaborative study with the NEI in which patients with retinitis whose CD4+ T-cell counts increase in response to the new therapies discontinue anti-CMV therapy. In other studies, samples from patients with possible opportunistic infections continue to be accumulated for the development of diagnostic assays. An assay using two highly specific probes for Pneumocystis carinii is being evaluated in respiratory specimens (oral washes, sputum, and bronchoalveolar lavages) from patients with and without Pneumocystis pneumonia and in healthy volunteers. A specific probe for CMV is being evaluated in buffy coats from CMV-infected and uninfected patients. Techniques to adapt both assays to clinical laboratories are actively being developed. Specimens from patients with Mycobacterium avium infection are being collected for use in the development of molecular probes for diagnosis and monitoringBecause NIAID researchers found that IL-12 improves control of M. avium complex (MAC) infection in mice, we have initiated a study of IL-12 in HIV-infected patients with disseminated MAC infection in which we will evaluate the safety, and the immunologic and microbiologic effects of IL-12 in combination with anti-MAC antibiotics. Access to clinical trials by local minority populations has been improved through an outreach program that includes a close relationship with a local clinic for the medically under-served. The assessment and long-term follow-up of persons with idiopathic CD4+ T-lymphocytopenia (ICL) continues to define their prognosis and the relationship between CD4+ T-cell counts and infections in this population.